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JP-7854633-B2 - Adhesive kit, method for manufacturing substrate with adhesive layer, and method for manufacturing article

JP7854633B2JP 7854633 B2JP7854633 B2JP 7854633B2JP-7854633-B2

Inventors

  • 白木 慶彦
  • 横山 英明

Assignees

  • 東ソー株式会社
  • 国立大学法人 東京大学

Dates

Publication Date
20260507
Application Date
20211201

Claims (2)

  1. A first step involves applying a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less onto a substrate containing a polyolefin to form a first layer containing the low molecular weight polyolefin. A second step involves applying a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms onto the first layer to form a second layer containing the polyurethane, A method for manufacturing a substrate with an adhesive layer, including the method described above.
  2. A first step involves applying a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less onto a substrate containing a polyolefin to form a first layer containing the low molecular weight polyolefin. A second step involves applying a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms onto the first layer to form a second layer containing the polyurethane, A third step is to place the adherend on the second layer to obtain a laminate comprising the substrate, the first layer, the second layer, and the adherend, A fourth step involves heating the laminate to obtain an article in which the substrate and the adherend are joined together, A method for manufacturing articles, including

Description

This invention relates to an adhesive kit, a method for manufacturing a substrate with an adhesive layer, and a method for manufacturing an article. Resin substrates containing polyolefins such as polypropylene are widely used industrially. Compared to metal materials, resin substrates have advantages such as being lightweight, inexpensive, and easy to mold and process. Generally, resin substrates are known to be less wettable than metal substrates. This poor wettability (hereinafter referred to as poor wettability) can cause defects such as adhesive repellency during application. Furthermore, substrates exhibiting poor wettability are generally known to exhibit poor adhesion, which also contributes to poor adhesive bonding. Therefore, studies have been conducted to improve adhesion to adhesives by changing the composition of the substrate, modifying the surface, and other methods. For example, Patent Document 1 describes a method for obtaining a modified polyolefin resin composition with improved properties such as adhesion by melt-kneading a radical polymerization initiator, an unsaturated carboxylic acid monomer, and an aromatic vinyl monomer with a polyolefin resin. However, this method requires replacing the material of the conventional resin substrate, which presents problems in terms of practicality and cost. Japanese Patent Publication No. 2009-13230 The following describes preferred embodiments of the present invention in detail. (Adhesive kit) The adhesive kit of this embodiment comprises a first agent containing a low molecular weight polyolefin with a weight-average molecular weight of 100,000 or less, and a second agent containing a polyurethane having a hydrocarbon group (i) with 40 or more carbon atoms in its main chain. According to the adhesive kit of this embodiment, an adhesive layer can be easily formed on a substrate by sequentially forming a coating film of the first agent and a coating film of the second agent on the substrate. The adhesive layer formed from the adhesive kit of this embodiment exhibits strong adhesion to polyolefin at a low heat treatment temperature (e.g., 130°C or below) because the first agent contains a low molecular weight polyolefin and the second agent contains a specific polyurethane. Therefore, the adhesive kit of this embodiment can be suitably used as an adhesive kit for forming an adhesive layer on a substrate containing polyolefin. The first agent contains a low molecular weight polyolefin. The weight-average molecular weight of the low molecular weight polyolefin is 100,000 or less. From the viewpoint of easily obtaining strong adhesion at lower heat treatment temperatures, it may be 90,000 or less, 80,000 or less, 70,000 or less, 60,000 or less, 50,000 or less, 45,000 or less, 40,000 or less, 35,000 or less, 30,000 or less, 25,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, or 9,000 or less. Furthermore, the weight-average molecular weight of the low molecular weight polyolefin may be, for example, 1000 or more. From the viewpoint of optimizing the melting point of the low molecular weight polyolefin, it may be 2000 or more, 3000 or more, 4000 or more, 5000 or more, 6000 or more, or 7000 or more. The weight-average molecular weight of low molecular weight polyolefins is the value measured by gel permeation chromatography (GPC) under the following conditions. <Measurement of weight-average molecular weight of low molecular weight polyolefins> The apparatus used was a high-speed GPC spectrometer (HLC-8321GPC/HT, manufactured by Tosoh Corporation). The columns used were one TSKgel guardcolumn HR (30)HT (7.5 mm I.D. × 7.5 cm) and three TSKgel GMH HR -H (20)HT (7.8 mm I.D. × 30 cm), connected in series in the order listed (all columns were manufactured by Tosoh Corporation). The mobile phase was 1,2,4-trichlorobenzene with 0.05% by mass of dibutylhydroxytoluene added, and the mobile phase rate was set to 1.0 mL/min. The column temperature was 140°C, and the detector was an RI detector (polarity (-)). The molecular weight was determined as polystyrene-equivalent molecular weight. The sample solution was prepared using 1,2,4-trichlorobenzene to a concentration of 1 mg/mL. The sample injection volume was 300 μL. Low molecular weight polyolefins may include, for example, polyethylene, polypropylene, ethylene propylene rubber, ethylene propylene diene rubber, etc. The low molecular weight polyolefin is preferably the same type of polyolefin as the polyolefin contained in the substrate on which the adhesive layer is formed. That is, if the polyolefin in the substrate is polyethylene, the low molecular weight polyolefin is preferably polyethylene; and if the polyolefin in the substrate is polypropylene, the low molecular weight polyolefin is preferably polyethylene. The first agent may further contain a solvent. The solvent should be any solvent capable of dissolving low molecular weight polyolefins. Examples of solvents include aromatic hydrocarbon so